I Legion. Praetor Uriens Durant looked across the cramped interior of of his Spartan command tank at the vexilla mounted to Sergeant Levarre’s powerpack. Such a simple design, he mused to himself. A bronze plaque bearing the ancient numeral I in silver bas relief, surmounted by a skull. The “I” overlaid a series of lightning bolts, chased in silver. The vexilla was old, as old as the Praetor, nearly 100 Terran Standard. Almost as old as the Legion. Weathered. Pitted. It showed a patina of experience, like the faces of the men sharing the compartment. Lavarre had been entrusted with it nearly 40 years ago. 40 years. Prior to that, it was Durant’s to carry. Durant trusted the simplicity of it. He had been inducted into the legion with that vexilla, and had followed it, carried it, and lead it through battle after battle. It was one of the first. That simple vexilla had been in battle throughout the Sol system, and then into the greater beyond. It had been at the front of the Great Crusade, and Uriens with it. Simple, straightforward. The I Legion.

I Legion

60 seconds.
The enemy would not have time to react.

50 seconds.
The swarm of Caestus and Kharybdis boarding rams had been launched from the Spear of Light via magnetic catapults. 100km away from the enemy vessel, the pilots engaged their thrusters. The enemy would not have time to react.

45 Seconds
Centurion Navarre could tell that Legionnaire Acteon was quietly counting the seconds to impact. Acteon's count was always dead on, even without a tactical feed such as the one that Navarre had. Tactical display indicated 45 seconds to impact. Navarre signaled his Astartes.

40 seconds.
While outwardly calm, even Astartes became excited. 35 seconds to impact, and Navarre could see an increase in heart rhythms, a minor increase in breath rate. Even Astartes got excited. "Focus that, brothers," Navarre thought.

30 seconds to impact.
Navarre's squad were Breachers. Selected from some of the most stalwart and skilled Astartes from the I Chapter's Assault squads. Navarre allowed himself a glimmer of pride in his warriors. In boarding actions, there where none outside of the Cataphractii who were more successful.

25 seconds.
Clad in reinforced armor, void hardened and trained. His armored boots had electromagnets built in, and they held him in place on the floor of the Caestus Ram as if he were part of it. In microgravity there is no "up" or "down", and without the electromagnets holding him down, he and his squad would be floating inside the bay. There were no viewports in the bay of the ram, but Navarre did not need them to know that his pilot was throwing the ram into complex spirals to avoid the close in defensive fire from the enemy vessel. He could feel the modulations in the thrusters through the soles of his feet.

20 seconds.
The pilot sounded the collision warning. Navarre's armor made a sudden hissing noise as it sealed. Audible only to him, the collision warning was also the signal that the ram was venting the atmosphere from the compartment. When the ram breached the enemy hull, the Astartes would be entering from the void. The misericordia system clamped down on their armor, stabilizing them for the upcoming impact. It would release as soon as the ram came to a full stop. The compartment ramps would open, and Navarre's squad would pile out. Depending on the interior layout of the ship , they would form either a delta or enfilade. Acteon on point.

15 seconds.
Navarre toned the ready chime for his Astartes. The silent compartment took on a sudden azure glow as the squad powered their weapons up. Navarre insisted that his breachers carry only the best weapons available. His unit was one of the few outside of the Cataphractii that still had regular access to Volkite weaponry. The I Legion, like all of the others, was phasing in the use of boltguns. While the boltguns were good weapons, Volkite weapons were much more suited to the shock of a boarding action. The short range of the beam was not a hinderance in the close in fighting of a ship. The beam from a Volkite could incinerate a man in less than a second, and the intensity of the fire could jump from target to screaming target. Terror was their name.

10 Seconds.
Navarre felt the discharge of the ram's missile payload through his feet. A steady ripple of plasma warhead missiles, designed to dig a hole in the hide of the enemy vessel. When the ram was close enough, the pilot would fire the magna-melta, and punch that hole even further, and then the ram would smash in.

5 Seconds.
Even Astartes became excited. Even a Centurion. Navarre felt his own heartbeats increase in speed. His tightened his grip on his boarding shield.

4 Seconds.
His brought his weapon up. The enemy would not have time to react.

3 seconds.
He pushed his feet against the floor, ready.

2.
The magnamelta fired.

1.
I Legion.